Fluid-pressure impact-tool.



No. 760,195. l PATENTED MAY 17, 1904. c. R. GREEN.

PLUIE PRESSURE IMEAGT T001.. APPLICATION FILED DEO. 2. 1903.

N0 MODEL.

T TUHNEYI t/l (um, INVENTUH.

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any suitable manner. As shown, the rearend- Y UNITED STATES 'rarentea May 17, 1904.

PATENT OFFICE.

FLUID-PRESSURE IMPACT-Tool..

SPECIFICATION forming pert'pf Lettere Patent No. 760,195, dated May 17,1904.

Applicationjiled December 2, 1903. Serial No. 183,436. (No model.)

To o/,ZZ` whom it may concern: l,

Be it known that I, CARL R.' GREEN, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and usefulv Improvement in :Fluid-Pressu re Impact-Tools, of which the following is-a specification.

My invention relates to long-,stroke powerhammers operated by air or other fluid under pressure, and especially to that class of such tools in which the How ofmotive fluid to the opposite ends of the cylinder is controlled by a reciprocating valve, one object of myinvention having been to devise novel means for insuring the quick and positive reciprocation ofthe valve at the proper times and a further object having been to simplify and cheapen the construction of the tool by employing therein the fewestparts consistent with efficient action, the parts being of strong and substantial construction, so that ,they are not likely to be injured or renderedino'perative by the rough handling to whichy these tools are subjected by the unskilled labor generally employed for operating them, the tool, moreover, being constructedwith special reference to readily replacing those parts which are subjected to wear. e

In the accompanying drawings, forming a part of the application, Figure 1 is a longitudinal section of a power-hammer intended to be operatedl by fluid-pressure and constructed in accordance with my invention. Fig. 2 is a view of the valve and the adjacent parts of the hammer, said parts' being in section,as.in Fig. 1, and the valve being in vits shifted position. Figs. 3, 4,*and 5}a'r'e transverse sections through the hammer on the lines 3 3, 4 4, and 5:5, respectively, of Fig. 1;, and Fig. Gis a fragmentary sectionalviewon the line 6 6 of Fig. 1. Y

responding parts throughout the several views of the drawings, in vwhich] 1 represents 4the hollow barrel, and 2 the detachable handle structure, that may be secured tothe barrel in of the barrel sits in a socket in the handle and is held securely in place by a flanged collar 3, that engages with the barrel andis secured to ,n to the rear again; Similar reference characters designatefcor-7 the handle. 'Io prevent rotation of the barrel in the socket and to secure perfect alinement` of the parts, the barrel and handle are each provided with small registering sockets, in'

which a short pin is placed, as shown at 4. The barrel is provided with a central bore5,

in which reciprocates the piston 6,' said piston being adapted to strike the rivet set or other tool 7, that is mounted in the forward end of the barrel. Y

y Within the handle 2, near the rear end of the barrel and extending substantially at right anglesV thereto, is a valve-chest 8, in' which is adapted to reciprocate a double-piston valve-f 9, the pistons being at the opposite ends' of the valve and being connected by a stem 10. For a reason hereinafter madeto appear the lower piston is of a slightly larger diameter than the upper one. f

The handle 2 contains a passage 11 for live air or other' suitable fluid, which communicates at its rear end with the usual flexible conductor, so that air under pressure maybe conducted to the hammer, the iow of air intoand through the passage 11 being controlled by a throttle-valve 12 andv a triggerl in a manner commonk to this class of tools. With the valve in the position shownin Fig. 1 the passage 11 communicates direct with the rear end of the bore 5 througha port 14,'and the compressed airacts'to drive thepiston forwardlyagainst the ltool 7. VVhenthevalve vis shifted, as in Fig. 2, the said-port 14 iis air infront of* the piston results in driving it n It will be noticed that the ports `leading to the forward end of the bore 5 are smaller than the port 14, sothat the hammer will not be driven` rearwardly "with the same velocity that it is driven forwardly. As the piston 6 moves forward from itsposition (shown in Fig. 1) the air in the front end of the barrel is exhausted through a series of ports 21, that communicate through ports22 and 23 Awiththe 'outside air, the multiplicity of these ports permitting a very rapid forward movement of the piston. The ports 21 terminate a short distance to the rear of the' tool 7, so that a small portion of the air in the barrel is confined and compressed by the piston near the forward end of the stroke. This compressed air acts backwardly through the ports 18, 17 and 16 against the larger piston of the valve and lifts the latter to the position shown in Fig. 2, which cuts o the live air from behind and admits it to the front of the piston, as heretofore described. The compression of the air between the piston and the tool will of course weaken the impact of the former, and it should be continued only to the point that is necessary to effect the movement of the valve. For this reason I have provided the opening 20, that communicates between the bore 5 and the port 18, said opening being-separated from the opening 19 a distance slightly greater than the length of the piston 6, so that the compressed air in the front end of the barrel may escape to the rear of the piston if the pressure is lower there, although it will be remembered that the air behind the piston is prior to the shifting of the valve in direct communication with the passage 11. The pressure from the air that is thus confined in front of the piston is sufiicient to shift the valve or to raise the pressure in the ports 18, 17 and 16 'practically to that required for shifting the valve, so that the admission of live air through the opening 20 will instantly result in moving the valve. At this instant the valve has live-air pressure on both pistons; butas the lower piston is oflarger diameter than the 'upper piston the excess pressure on the l'ower piston will move the valve upwardly. The air being admitted-to the front of the piston thrugh the ports 15, 16, 17, 18, and 19, the piston will be driven to the rear, the air escaping from the rear en'd of the barrel through the ports 24 at either side thereof, as shown more particularly in Fig. 4 of the drawings. These ports 24 communicate with the valve-'chest 8 through port 30 just below the upper piston of the valve when it is in its upper position, so that the air may reach and pass out through the exhaust -port 23. At this time the exhaust-ports 21 and 22 are closed by the lower piston of the valve, said piston resting with its upper edge against a seat 25 in the valve-chamber.

While it is desirable to move the piston 6 rearwardly as rapidly as practicable, provi-l sion must be made for bringing the same to a stop slowly. For this reason the port 24 has its opening into the barrel some distance from the rear end of the cylinder, as shown at 31, so that the piston will cut 0E the escaping air and compress the remaining portion in the rear end of the cylinder. The air compressed by the piston 6 at this time acts against the smaller piston of the valve 9 through port 14 to shift it downwardly; but it is opposed by live-air pressure on the larger piston of the valve, which is connected to the front end of the cylinder 5 by ports '16, 17, 18, and 19. As these ports are larger than port 15, which supplies air to return the piston, the air is wiredrawn through port 15, so that the air behind piston 6 is compressed to a higher unit-pressure than the air in front of it, and therefore the total pressure on the smaller end of the valve is greater than the total pressure on the larger end, and the valve is thereby shifted downwardly.

From the foregoing description it will be seen that when the piston 6 is traveling forward the smaller end of the valve has a pressure of live air against it, while the larger end is in direct communication with the atmosphere until ports 21 are closed by piston 6, and that while the piston is traveling backward the large end of the valve has a pressure of live air against it, while the smaller end is in direct communication with the atmosphere until ports 24 are closed by piston 6. It will also be seen that the space between the two pistons of valve 9 is always in direct communication with the atmosphere through port 23.

The valve-chest is closed at its lower end by a plug-nut 26, on the inner side of which is a boss 27, against which the valve rests when in its lower position, the boss and the seat 25 determining the extent of movement of the valve.

It sometimes happens in dcvicesof this character that the trigger 13 is accidentally depressed and the piston driven forward without having the tool 7 braced, with the result that the tool and piston are blown away. To prevent this, I provide the handle with a locking-bolt 28, that is normally held bya spring 29 in position to intercept the lower end of the trigger, so that it cannot be depressed. When the operator grasps the handle, however, he presses the locking-bolt inwardly, as shown in Fig. 6, so as to bring a groove in the same in line with the trigger, which can then be operated to open the valve 12.

From this description it will be seen thatI have provided a hammer with a very simple valve that is arranged at right angles to the length ofthe barrel, so as to shorten the tool.

`The smaller piston of the valve controls the r1`he lower piston is of larger i IOO IIO

plementing the pressure of the compressed air to facilitate the shifting of the valve.

2. A fluid-pressure power-hammer having a cylinder with reciprocating hammer therein, a Valve-chest having a double-piston valve which controls the iow of motive vfluid into and its exhaust from each end of the said cylinder, that piston of the valve at one end being less in diameter than the piston at the opposite end, and the exhaust-passages communicating with the cylinder some distance from 20 the ends of the same, whereby movement lof the valve in one direction is effected by air compressed in the forward end of the cylinder and acting upon the larger piston of the valve and movement in the opposite direction is effected by air compressed in the rear end of the cylinder and acting upon the smaller piston of the valve,V lthe valve-controlled passage for conveying motive fluid to the rear end of the cylinder being of greater area' than that which conveys motive fluid to the forward end of the cylinder,` substantially as specified.

In testimony whereof I ailiX my signature in the presence of two witnesses.

' CARL R. GREEN.

Witnesses:

D. J. DWYER, C. M. HARPER. 

